(1) Field of the Invention
This invention relates to apparatus for the chemical analysis of substances, and more particularly, to a mechanism for advancing an analysis slide through a plurality of work stations in a chemical analyzer.
(2) State of the Prior Art
Recent developments have provided analysis slides for use in performing quantitative analyses of biological fluids. The slides are essentially planar, contain reagents in a dry form, and can be loaded into a cartridge for use in a chemical analyzer. In the operation of such an analyzer, an analysis slide is fed from a cartridge into a metering station where a predetermined amount of fluid is deposited on the analysis slide. After an appropriate incubation period, the slide is moved to an analysis station where a change in the slide is sensed, the amount of change being proportional to a particular analyte in the sample fluid. The slide is used only once and is discarded after the reading has been taken. An analyzer for use with slides of this type is described in commonly-assigned U.S. Pat. No. 4,152,390, granted on May 1, 1979.
Apparatus for use with analysis slides of the type described above can be made relatively small, and in some cases portable, since no liquid reagents are used which require intricate solution handling and transport capabilities. In small apparatus of this type, certain advantages result from providing simple, manually-operated mechanisms for advancing analysis slides from station to station. An example of such a slide transfer mechanism is shown in the aforesaid U.S. patent application Ser. No. 927,702, in which a single elongate member, mounted for slidable movement, is used to advance an analysis slide along a track which extends through each station of the analyzer. Such a transfer mechanism works well with a low-capacity analyzer. However, each slide must be manually inserted in the track, and thus, the mechanism is not suitable for use in semi-automatic analyzers where a relatively high throughput is desired.
The U.S. Pat. No. 4,110,167, to Melnyk, granted on Aug. 29, 1978, discloses a "semi-automated" slide processor device in which a slide bar is manually actuated to advance slides through the device. The slide bar is adapted to advance slides by pushing new slides from a slide supply into engagement with slides being processed in the device. Such a method of moving slides can cause undesirable agitation of fluids carried on the slides; further, there is no way to clear the device of slides, since new slides must be used to advance the processed slides. Slides left in the apparatus between runs are subject to contamination which can, of course, affect the test results.